1. Field of the Invention
This invention relates generally to optical systems for scanning an object and reproducing an image thereof, and more particularly the invention relates to a laser scanning system in which the size of a reproduced image may be electronically varied.
2. Prior Art
Various optical systems for scanning an object and reproducing an image thereof are known in the prior art. The Laserite system commercially available from EOCOM Corporation of Irvine, Calif. (assignee of this application) uses a laser scanner which develops an image signal by linearly scanning an object. The image signal controls a second laser scanner which develops the image of the object. The system has many applications including the setting of printing type, for example.
The optical system of the Laserite scanning system is disclosed in pending U.S. application Ser. No. 758,250 filed Jan. 10, 1977. In the described system the generated image signal is applied to a modulator which controls the beam intensity of the second laser which scans an image or output copy plane simultaneously as the first laser scans the object or input copy plane.
In pending application Ser. No. 695,921 filed June 14, 1976, now U.S. Pat. No. 4,081,842 another embodiment of the Laserite system is disclosed in which the image signal is applied to a photomultiplier tube which generates a video data signal. The video signal is applied through computer means to control the write laser scanner which develops the image or facsimile of the object. This system provides freedom from reliance on time synchronization which allows greater flexibility of operation.
In the prior art systems variations in size of the projected image have been accomplished optically by modifying lens focal lengths and linear scan distances. Such techniques are complex and require suitable lenses for substituting into the system.